U.S. Pat. No. 5,558,178 discloses that data can be exchanged between various control units for controlling a motor vehicle. The data can be exchanged, for example, via a data bus such as CAN. In this patent, a control system for the drive unit of a motor vehicle is described to which, in specific operating states, input values for the torque of the drive unit are transmitted from at least one additional control unit. The at least one additional control unit defines at least one of the following: a control unit for carrying out a drive-slip control, a driving dynamic control, an electronic transmission control unit or a control unit for controlling the distance to a forward vehicle. The desired torque values, which are transmitted in this way, are converted by the motor control unit so that the torque of the drive unit approximates the externally supplied desired value in the above-mentioned operating states. The consistency or actuality of the transmitted data is then of special significance.
To monitor the actuality of the transmitted data, a message count is transmitted from the additional control unit at time points which changes regularly and the motor control unit checks the actuality of the transmitted data on the basis of this message count. To check consistency of the input values, plausibility checks are provided from which the correctness of the transmitted desired torque values can be derived with great probability.